Nearby terms:

delayed control-transfer

A technique used on the SPARC processor to reduce
the effect of pipeline breaks by executing the instruction after
a branch instruction (the "delay instruction" in the "delay
slot"). If there is no useful instruction which can be placed in
the delay slot then the "annul bit" on the control transfer
instruction can be set, preventing execution of the delay
instruction (unless the control transfer is conditional and is
taken).

Annulled branches are indicated in SPARC assembler language by
appending ",A" to the operation code. For example,

LOOP: ...
CMP %L0,10
BLE,A LOOP
ADD %L2, %L3, #L4

If the delay instruction is also a control transfer instruction
then it gets more complicated. Both control transfer instructions
are executed (but not the following instruction) and, assuming
they are both taken, control is transferred briefly to the
destination of the first and then immediately to the destination
of the second.

Nearby terms:

delete

Usually this operation only deletes information from the
tables the file system uses to locate named files; the
file's contents still exist on disk and can sometimes be
recovered by scanning the whole disk for strings which are
known to have been in the file. Files created subsequently on
the same disk are quite likely to reuse the same blocks and
thus overwrite the deleted file's data permanently.

2. The control character with ASCII code 127.
Usually entering this character from the keyboard deletes the
last character typed from the input buffer. Sadly there is
great confusion between operating systems and keyboard
manufacturers as to whether this function should be assigned
to the delete or backspace key/character.

The choice of code 127 (binary 1111111) is not arbitrary but
dates back to the use of paper tape for input. The delete
key rewound the tape by one character and punched out all
seven holes, thus obliterating whatever character was there
before. The tape reading software ignored any delete
characters in the input.

Delivered Source Instruction

DSI is the primary input to many tools for estimating software
cost. The term "delivered" is generally meant to exclude
non-delivered support software such as test drivers. However,
if these are developed with the same care as delivered
software, with their own reviews, test plans, documentation,
etc., then they should be counted. The "source instructions"
include all program instructions created by project personnel
and processed into machine code by some combination of
preprocessors, compilers, and assemblers. It excludes
comments and unmodified utility software. It includes job
control language, format statements, and data declarations.

Nearby terms:

Delphi Technique

A group forecasting technique, generally
used for future events such as technological developments,
that uses estimates from experts and feedback summaries of
these estimates for additional estimates by these experts
until reasonable consensus occurs. It has been used in
various software cost-estimating activities, including
estimation of factors influencing software costs.

Nearby terms:

delta

1. A quantitative change, especially a small or incremental
one (this use is general in physics and engineering). "I just
doubled the speed of my program!" "What was the delta on
program size?" "About 30 percent." (He doubled the speed of
his program, but increased its size by only 30 percent.)

2. [Unix] A diff, especially a diff stored under the set
of version-control tools called SCCS (Source Code Control
System) or RCS (Revision Control System). See change
management.

3. A small quantity, but not as small as epsilon. The
jargon usage of delta and epsilon stems from the
traditional use of these letters in mathematics for very small
numerical quantities, particularly in "epsilon-delta" proofs
in limit theory (as in the differential calculus). The term
delta is often used, once epsilon has been mentioned, to
mean a quantity that is slightly bigger than epsilon but
still very small. "The cost isn't epsilon, but it's delta"
means that the cost isn't totally negligible, but it is
nevertheless very small. Common constructions include "within
delta of ---", "within epsilon of ---": that is, "close to"
and "even closer to".

Nearby terms:

delta reduction

In lambda-calculus extended with constants, delta
reduction replaces a function applied to the required number
of arguments (a redex) by a result. E.g. plus 2 3 --> 5.
In contrast with beta reduction (the only kind of reduction
in the pure lambda-calculus) the result is not formed simply
by textual substitution of arguments into the body of a
function. Instead, a delta redex is matched against the left
hand side of all delta rules and is replaced by the right hand
side of the (first) matching rule. There is notionally one
delta rule for each possible combination of function and
arguments. Where this implies an infinite number of rules,
the result is usually defined by reference to some external
system such as mathematical addition or the hardware
operations of some computer. For other types, all rules can
be given explicitly, for example Boolean negation: